Johnson Pump 5.0GPM Flow Master Variable Flow Pump - 24V [10-13329-104]5. 0GPM Flow Master Part #: 10 13329 104 The Flow Master 5. 0 is a five chamber positive displacement diaphragm pump that is an ideal choice for pressurizing water in a closed system such as that found in a boat or Recreational Vehicle (RV). The digital controller adjusts water flow as the demand is increased and decreased while maintaining a very smooth flow. The unique variable flow feature of the Flow Master pump allows the pump to be mounted